<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
    <style>
        body{
            padding: 0;
            margin: 0;
        }
        .sky{
            -webkit-box-sizing: border-box;
            -moz-box-sizing: border-box;
            box-sizing: border-box;
            width: 200px;
            height: 200px;
            background-color: green;
            border: 10px solid red;
            padding: 20px;
        }
        .moon{
            color: yellow;
            width: 200px;
            height: 200px;
            background-color: green;
            border: 10px solid ;
            padding: 20px;
        }
    </style>
</head>
<body>
<div class="sky">
    标准模式
</div>
<div class="moon">
    怪异模式
</div>
</body>
</html>